Sea lion

Key takeaways

Sea lion belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Sea lion to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Sea lion from memory before moving on to harder problems.

Reference excerpt

Sea lions are pinnipeds characterized by external ear flaps, long foreflippers, the ability to walk on all fours, short and thick hair, and a big chest and belly. Together with the fur seals, they make up the family Otariidae, eared seals. The sea lions have six extant and one extinct species (the Japanese sea lion) in five genera. Their range extends from the subarctic to tropical waters of the global ocean in both the Northern and Southern hemispheres, with the notable exception of the northern Atlantic Ocean. Sea lions have an average lifespan of 20–30 years. A male California sea lion weighs on average about 300 kg (660 lb) and is about 2.4 m (8 ft) long, while the female sea lion weighs 100 kg (220 lb) and is 1.8 m (6 ft) long. The largest sea lions are Steller's sea lions, which can weigh 1,000 kg (2,200 lb) and grow to a length of 3.0 m (10 ft). Sea lions consume large quantities of food at a time and are known to eat about 5–8% of their body weight (about 6.8–15.9 kg (15–35 lb)) at a single feeding. Sea lions can move around 16 knots (30 km/h; 18 mph) in water and at their fastest they can reach a speed of about 30 knots (56 km/h; 35 mph). Three species, the Australian sea lion, the Galápagos sea lion and the New Zealand sea lion, are listed as endangered.

Taxonomy

Sea lions are related to walruses and seals. Together with the fur seals, they constitute the family Otariidae, collectively known as eared seals. Until recently, sea lions were grouped under a single subfamily called Otariinae, whereas fur seals were grouped in the subfamily Arcocephalinae. This division was based on the most prominent common feature shared by the fur seals and absent in the sea lions, namely the dense underfur characteristic of the former. Recent genetic evidence, suggests Callorhinus, the genus of the northern fur seal, is more closely related to some sea lion species than to the other fur seal genus, Arctocephalus. Therefore, the fur seal/sea lion subfamily distinction has been eliminated from many taxonomies. Nonetheless, all fur seals have certain features in common: the fur, generally smaller sizes, farther and longer foraging trips, smaller and more abundant prey items, and greater sexual dimorphism. All sea lions have certain features in common, in particular their coarse, short fur, greater bulk, and larger prey than fur seals. For these reasons, the distinction remains useful. The family Otariidae (Order Carnivora) contains the 15 extant species of fur seals and sea lions. Traditional classification of the family into the subfamilies Arctocephalinae (fur seals) and Otariinae (sea lions) is not supported, with the fur seal Callorhinus ursinus having a basal relationship relative to the rest of the family. This is consistent with the fossil record which suggests that this genus diverged from the line leading to the remaining fur seals and sea lions about 6 million years ago (mya). Similar genetic divergences between the sea lion clades as well as between the major Arctocephalus fur seal clades, suggest that these groups underwent periods of rapid radiation at about the time they diverged from each other. The phylogenetic relationships within the family and the genetic distances among some taxa highlight inconsistencies in the current taxonomic classification of the family. Arctocephalus is characterized by ancestral character states such as dense underfur and the presence of double rooted cheek teeth and is thus thought to represent the most "primitive" line. It was from this basal line that both the sea lions and the remaining fur seal genus, Callorhinus, are thought to have diverged. The fossil record from the western coast of North America presents evidence for the divergence of Callorhinus about 6 mya, whereas fossils in both California and Japan suggest that sea lions did not diverge until years later.

Suborder Caniformia Family Otariidae Subfamily Arctocephalinae Genus Arctocephalus (southern fur seal; eight species) Genus Callorhinus (northern fur seal; one species) Subfamily Otariinae Genus Eumetopias Steller's sea lion, E. jubatus Genus Neophoca Australian sea lion, N. cinerea Genus Otaria South American sea lion, O. flavescens Otaria josefinae Genus Phocarctos New Zealand sea lion or Hooker's sea lion, P. hookeri Genus Zalophus California sea lion, Z. californianus Japanese sea lion, Z. japonicus – extinct (1950s) Galapagos sea lion, Z. wollebaeki Family Phocidae: true seals Family Odobenidae: walrus

Physiology

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Sea lion

Start with the simplest possible case. Write down what Sea lion claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Sea lion before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Sea lion ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Sea lion

In research: Sea lion appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Sea lion in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Sea lion is common in secondary-school and first-year university syllabi. It links to neighbouring topics Fur trade, Mammal common names, Paraphyletic groups, so understanding it makes those chapters shorter.
In everyday life: Look for Sea lion outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study Sea lion in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Sea lion means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Sea lion out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Sea lion in simple terms?

Sea lions are pinnipeds characterized by external ear flaps, long foreflippers, the ability to walk on all fours, short and thick hair, and a big chest and belly. Together with the fur seals, they make up the family Otariidae, eared seals.

Why does Sea lion matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Sea lion?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Sea lion.